POTENTIAL BILE-ACID METABOLITES .20. A NEW SYNTHETIC ROUTE TO STEREOISOMERIC 3,6-DIHYDROXY-5-ALPHA-CHOLANOIC AND 6-HYDROXY-5-ALPHA-CHOLANOIC ACIDS

An improved procedure for the syntheses of stereoisomeric 3,6-dihydrox y- and 6-hydroxy-5alpha-cholanoic acids (and their methyl esters) is d escribed. The principal reactions employed are those reported in the p receding paper of this series, with the commercially available hyodeox ycholic acid as starting material. The final step in the procedure is the reduction of the key 5alpha C-6 ketones with either the stereosele ctive equatorial reagent, Li/NH3/MeOH, or the axial reagent, Zn(BH4)2. The results of analysis of the prepared 6-monohydroxylated and 3,6-di hydroxylated stereoisomers by thin-layer chromatographic, high perform ance liquid chromatographic and gas-liquid chromatographic mobilities, and H-1 and C-13 nuclear magnetic resonance spectra are discussed alo ng with the data for the corresponding compounds in the 5beta-series.